Characteristics of ocean waters reaching Greenland's glaciers

Interaction of Greenland's marine-terminating glaciers with the ocean
has emerged as a key term in the ice-sheet mass balance and a
plausible trigger for their recent acceleration. Our knowledge of the
dynamics, however, is limited by scarcity of ocean measurements at the
glacier/ocean boundary. Here data collected near six
marine-terminating glaciers (79 North, Kangerdlugssuaq, Helheim and
Petermann glaciers, Jakobshavn Isbrae, and the combined Sermeq
Kujatdleq and Akangnardleq) are compared to investigate the water
masses and the circulation at the ice/ocean boundary. Polar Water, of
Arctic origin, and Atlantic Water, from the subtropical North
Atlantic, are found near all the glaciers. Property analysis
indicates melting by Atlantic Water (AW; found at the grounding line
depth near all the glaciers) and the influence of subglacial discharge
at depth in summer. AW temperatures near the glaciers range from 4.58C
in the southeast, to 0.168C in northwest Greenland, consistent with
the distance from the subtropical North Atlantic and cooling across
the continental shelf. A review of its offshore variability suggests
that AW temperature changes in the fjords will be largest in southern
and smallest in northwest Greenland, consistent with the regional
distribution of the recent glacier acceleration.